Which component is not involved in varying the flow of refrigerant in a refrigeration system?

The solenoid valve primarily acts as a control device for the flow of refrigerant by opening or closing in response to electrical signals, but it does not actually vary the flow of refrigerant itself. Instead, it controls the flow by directing refrigerant to different parts of the system when necessary, rather than adjusting the flow rate.

In contrast, the expansion valve is responsible for reducing the pressure of the refrigerant, which directly affects the flow rate entering the evaporator. The compressor plays a crucial role in moving the refrigerant through the system, as it compresses the refrigerant, consequently affecting the flow rate and pressure throughout the system. The receiver, while it stores refrigerant in its liquid state, also does not primarily function to vary the flow of refrigerant but rather serves to separate the liquid from gas refrigerant and acts as a storage point for liquid refrigerant before it enters the expansion device. Understanding the specific roles of these components helps clarify why the solenoid valve does not function to vary the flow of refrigerant in the same way as the others.